1. Field of the Invention
The present invention relates to a display panel driver.
2. Description of the Related Art
In recent years, as the screens of display devices become larger, there is also a demand for thinner display devices, and various kinds of thin display devices have been put into practice. Plasma display panels (referred to in the following as “PDP”) have garnered attention as one type of thin display panel in which a plurality of discharge cells serving as pixels are arranged in a matrix. The discharge cells emit light by discharges, so that only two states, namely a “lighted state” in which they emit light at a predetermined luminance and an “unlighted state,” and thus only the luminance for two gradations, can be realized. In order to address this problem, a PDP 10 provided with such discharge cells is subjected to gradation driving using the sub-field method, which is supposed to realize the display of intermediate luminances corresponding to the input video signal.
In the sub-field method, the display period of one field is divided into N sub-fields, and the number of times that the discharge cells are supposed to discharge continuously is assigned in advance to each sub-field. Within each sub-field, the individual discharge cells are caused to discharge selectively in correspondence with the input video signal, performing an addressing step in which they are set either to a lighted cell state or an unlighted cell state, and an emission sustaining step in which only for the discharge cells that are in the lighted cell state the discharge emission is repeated for the number of times that has been assigned as described above. With this driving method, intermediate luminances that correspond to the total number of discharge emissions carried out in the emission sustaining steps within one field display period can be realized.
In plasma display devices, discharges are induced during the emission sustaining step for the actual image display, but also during the addressing step, and the current flowing in the course of this discharge leads to the consumption of power. Whether a discharge occurs in the discharge cells during this addressing step depends on the input video signal. Thus, there is the problem that, depending on the input video signal that specifies the image to be displayed, the power that is consumed in the addressing step may increase.